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Re: Semantics question (was Re: XSLT question)

From: Phil Archer <parcher@icra.org>
Date: Wed, 23 Apr 2008 15:07:29 +0100
Message-ID: <480F42A1.30605@icra.org>
To: Public POWDER <public-powderwg@w3.org>

I'm sorry Stasinos, this must be frustrating for you, but let me try this.

<owl:Restriction>
   <owl:onProperty rdf:resource="&bbfc;rated" />
   <owl:hasValue rdf:resource="&bbfc;_12" />
</owl:Restriction>

is OK iff

<rdf:Description rdf:about="&bbfc;_12">
   <bbfc:rated>12</bbfc:rated>
   <bbfc:consumerAdvice>May contain nuts <bbfc:consumerAdvice>
</rdf:Description>

Because bbfc:rated appears in the restriction and in the filler, but if 
we remove that bbfc:rated property from the rdf:Description, then it all 
falls apart?

My basic struggle here is that (as you know) we're trying to end up with 
triples that have the candidate resource as their subject. Given

<descriptorset>
   <ex:property rdf:resource="&ex;foo" />
</descriptorset>

and a candidate URI of u, well, it's easy to see

<rdf:Description rdf:about="u">
   <ex:property rdf:resource="&ex;foo" />
</rdf:Description>

as the output.

Dan and Jeremy went to great lengths to explain some restrictions on 
this when I saw them together in Bristol at the end of last year. This, 
for example, would be unacceptable:

<rdf:Description rdf:about="u">
   <ex:property>
     <ex:Class>
       <ex:property2 rdf:resource="&ex;foo" />
     </ex:Class>
   </ex:property>
</rdf:Description>

... it's the semantics of the blank node that mess this up - so we do 
already have limits on the expressivity of a DR's descriptor element, 
but being able to say

<descriptorset>
   <ex:property rdf:resource="&ex;foo" />
</descriptorset>

would be good to be able to do - even if we have to make clear the 
limitations of what &ex;foo can be.

P






Stasinos Konstantopoulos wrote:
> On Wed Apr 23 12:31:58 2008 Phil Archer said:
> 
>> The projectionist shining his beam on my ignorance is right to have the  
>> power setting at maximum...
>>
>> I followed the hyperlink to the OWL spec and, erm, sorry, I'm still a  
>> little unclear. Is this an 'individual'?
> 
> "individual" is just OWL parlance for "instance"
> In this here:
> 
>> <rdf:Description rdf:about="#bbfc12">
>>   <ex:property>value</ex:property>
>> </rdf:Description>
> 
> If ex:property is a datatype property, "value" is s'thing concrete like
> "43" or "yttrium".
> 
> If ex:property is an "object property" or "role", then value, the "role
> filler", is an abstract instance/individual, like
> "http://example.org/semantic/powder.rdf#d1"
> 
> s
Received on Wednesday, 23 April 2008 14:08:24 GMT

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